TITLE: GCN CIRCULAR
NUMBER: 24978
SUBJECT: GRB 190530A: Observation of the afterglow by NOEMA
DATE: 19/07/04 15:22:54 GMT
FROM: Antonio de Ugarte Postigo at IAA-CSIC
A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), M. Bremer (IRAM),
S. Schulze (Weizmann), C. C. Thoene, D. A. Kann, L. Izzo, M. Blazek,
K. Bensch (all HETH/IAA-CSIC), D. A. Perley (LJMU), S. Martin (ALMA),
I. de Gregorio-Monsalvo (ESO), M. Michalowski (AOI-AMU),
R. Sanchez-Ramirez (INAF-IAPS), D. B. Malesani (DTU Space) report:
We observed the field of the bright GRB 190530A (Fermi team GCN
24676) with NOEMA, at wavelengths between 76 and 150 GHz in 4
epochs, ranging between 31 May 2019, at 14:29 UT (1.17 days after the
burst) and 15 June 2019, at 20:54 UT (16.44 days after the burst). The
afterglow (discovered in the optical by Lipunov et al. GCN 24680) was
detected on the first epoch with a flux density of 1.0 mJy at 92 GHz. At
this time the peak frequency was located close to this observed frequency.
In the subsequent epochs the peak frequency of the synchrotron spectrum
was bluewards of the 76 GHz frequency band and the source declined
steadily in flux density until it was no longer detected in our latest
observation, which had an r.m.s of 0.066 mJy at the 92 GHz band.